There are two harmonica playing bluesmen known as Sonny Boy Williamson. They are colloquially referred to as Sonny Boy Williamson I and Sonny Boy Williamson II respectively, but are of no relation. The two are easy to distinguish. Williamson I played the harmonica acoustically and was essentially a pre-War artist. Williamson II was entirely an electrified harpist, in the style of Little Walter, reflecting the advent of the jukebox and electrified instruments following World War II.